The long-term goal of our research is to understand the biological bases of development of language and other cognitive functions. We have been investigating Williams syndrome, a rare genetically-based disorder that results in mental retardation. We have found that the syndrome also results in specific dissociations in cognitive functions, both within and across domains; (a) massive cognitive deficits but considerable sparing of language in adolescents and adults; and (b) extreme disorders in spatial cognition but excellent face processing. Moreover, our studies are finding that Williams syndrome leaves a distinctive morphological stamp on the brain, manifest in both neurophysiological and neuroanatomical findings. Contrasts in the Development of Language and Other Cognitive Domains. In the studies proposed here, we will examine developmental trajectories of language and other cognitive domains in Williams syndrome children age 5-12 years. The objective is to describe and compare the development of individual cognitive domains and their underlying neural bases. The study of developmental trajectories in Williams syndrome children can provide a new perspective on the relationships between domains of cognition and brain organization. While there is relative sparing of language (particularly syntax) ion the adolescents,, their language is not without anomalies (e.g., signs of unusual semantic organization). There are also morphological errors that persist. Developmentally, there are also anomalies: the Williams syndrome toddlers exhibit massive delays in language milestones. Our finding so far is that at least certain aspects of language in Williams syndrome do not really start flourishing until 10 years of age or so. One of the objectives of the research is to explore the nature of this selective recovery and to find links between the delay in onset in language and the anomalies that later surface. Intersection of Affect and Language in Discourse in Development. Williams syndrome adolescents make abundant usage of affective linguistic devices in discourse and display strong interest in social interaction. Preliminary observations of Williams syndrome children suggest that this affective profile may appear prior to the emergence of language. We will investigate the links between language and affect in development in this syndrome. Visual Based Cognition in Williams Syndrome: Peaks & Valleys in Development. Williams syndrome results in a highly specific dissociation in spatial cognition in which there is selective attention to details of a configuration at the expense of the whole. In contrast, face processing shows remarkable preservation across experimental paradigms. Thus, Williams syndrome can provide a powerful vehicle for investigating the developmental separability of functions within, as well as across, cognitive domains. Brain Organization in the Developing Williams Syndrome Child. Our research with Williams syndrome children and adolescents suggests that aspects of language and other cognitive functions may be mediated by neural systems that differ in major ways from those seen in normal populations. We will investigate the brain organization through combined measures of behavior and neurophysiology. The study of development in this rare disorder provides major contrasts with other populations studied in the Center. These studies will also provide crucial information for families, physicians and educators.